<?php
/**
 * Created by PhpStorm.
 * User: Administrator
 * Date: 2017/9/19
 * Time: 16:10
 */


function foo(){
    define("PI",3.14);
    echo PI."函数内部<br>";
}
foo();

function fun(){
    echo PI."函数内部fun<br>";
}
echo PI."函数外部<br>";
fun();